The present invention relates to an apparatus for testing physical characteristics of materials, especially for testing rolling contact fatigue resistance of materials. While using such an apparatus and thereby testing rolling contact fatigue resistance of certain material, a spherical tester, namely a testing ball, is rolled along a surface of a tested object under appropriate loading, whereby a certain number of repeats has to be executed and appropriate point contact between the aforementioned testing ball and the surface of the tested object has to be ensured.
The aim of the present invention is to create as much as possible simple apparatus, which shall be useful for testing the rolling contact fatigue resistance of materials and by which as much as possible various testing possibilities shall be available, so that in despite of testing of ordinary laboratory tested objects prepared in advance also quite satisfactory testing of different final products or parts thereof would be possible.
As known to those skilled in the art (and as e.g. shown in the technical description of the available testing apparatuses manufactured by FAG Kugelfischer Georg Schxc3xa4fer AG), the common used apparatuses for testing rolling contact fatigue resistance of materials mainly comprise a clamping unit, a loading unit and a driving assembly. However, with regard to discussion relating to the features of the present invention, the most important part is the loading unit, which is created as to enable placing the testing ba of appropriate diameter into a suitable bearing, by which the ball is placed in such a manner that it can rotate freely in all directions. In addition, the loading unit itself is also rotatable, so that the bearing and herewith also the testing ball can be revolved around the axis, whereby as a consequence appropriate movement of the testing ball is obtained in appropriate plane, namely cyclical movement along a circular trajectory of appropriate diameter. Furthermore, the loading unit is arranged to ensure certain loading, to which the testing ball is exposed while abutting the tested object. The clamping unit of such an apparatus is arranged for receiving and reliable clamping the tested object, particularly with regard to aforementioned loading of the testing ball as well as with respect to circular movement thereof during testing. The driving assembly comprises suitable driving and bearing parts, which at the defined loading of the testing ball on the surface of each tested object enable a suitable circulating of the testing ball on the surface of each tested object, clamped in the clamping unit.
Such an apparatus is relatively complicated, but in common it enables testing of the rolling contact fatigue resistance of materials. Nevertheless, in order to enable testing of certain material, a special tested object of appropriate material must be available, which comprise appropriate surface, which has to be large enough to enable circular movements of the testing ball on the surface of the tested object, whereby a certain number (e.g. several hundred thousands or even several millions) of cycles of rolling appropriate loaded testing ball along the surface of the tested object in a point contact between them is expected.
Such an apparatus should be used either for laboratory testing where appropriate tested objects prepared specially for this purpose are used, or even for testing of final products or e.g. assembling parts thereof, which may also be important in the industry. In certain cases, especially when testing certain materials (e.g. ceramics, noble and precious metals or similar) also the laboratory testing as such may involve various and serious problems. On the other hand, when testing different final products or parts thereof (except e.g. by testing of roll bearings or parts thereof) by such an apparatus, it is ordinary really difficult or quite impossible to find appropriate surface, which would be suitable for eccentrically turning and rolling a testing ball, as well as to ensure appropriate clamping of the tested object simultaneously.
According to the invention, an apparatus for testing physical characteristics of materials, especially rolling contact fatigue resistance of materials, comprises a loading unit, which is connected to a driving assembly and driven by it in such a manner, that a linear oscillatory movement of the loading unit is enabled, whereby appropriate tester, namely a testing ball, is rolled along the surface of a tested object, which is held in a clamping unit. Thereby, a loading unit preferably comprises a screw-rod, by means of which it can be connected to appropriate crank mechanism, which is furthermore connected to appropriate driving assembly and driven by it. While the point contact between the tester and tested object is ensured, the aforementioned testing ball can be linearly oscillatory rolled here and there along the surface of the tested object, by which the said testing ball is moreover loaded in appropriate manner by means of the loading unit comprising a bearing surface arranged adjacent to the tested object and equipped by a groove arranged in a rolling direction of the testing ball, whereby in the said groove the testing ball is placed.